Version 0.0.0 @ 03:55/08.07.2000

Related Terms

Application Layer: this is layer 7 of the ISO , OSI 7 layer model and layer 5 of the TCP/IP 5 layer model. It is responsible for application level protocols such as HTTP, NNTP, FTP, Telnet, DNS, SSH, SMB, and AFP to name a few.

bit: combination of the two words "binary" and "digit" where possible values are either 1, or 0 for on or off respectively.

byte: often a byte is a collection of 8 bits used to represent a number that maps to a special character or instruction.

checksum: a value derived from a calculation performed upon a sequence of numbers that when re-calculated ends up with the same value for the same sequence of numbers. This is used to verify that a set of data has not become corrupted between the time it was last used or created and the time it is being read.

Data Link Layer: With the ISO, OSI 7 layer model (or TCP/IP 5 layer reference model) this layer is responsible for providing an error free transmission of data. Examples of protocols that fit this in some parts include (but are not limited to): ATM, PPP, SLIP, EtherNet, TokenRing, SONET, xDSL, and ISDN.

Denial of Service: this is what happens when something stops working. Any service can be denied. If there is service in the McDonald's drive through, a denial of service for the fast-food drive-through might be cutting the wires that allow the speaker and microphone to relay communications between the sign and the window. Another might be to blow up the building, or something small like paying everyone to not show up at work, or go on strike. A denial of service is just what it states, a "denial of service" that prevents the normal functions of that service from operating. Usually a denial of service is not desired by the administrators of the service. Often there is negative association with this word and crackers. With physical access to a machine, nearly anyone can enact a denial of service by breaking a device. DoS need not have finesse, they can be blunt, or sophisticated.

DoS: See Denial of Service...

EtherNet: a common Data Link layer protocol created and described by IEEE 802.3, and 802.2. Common media types that use EtherNet include 10Base2, 10BaseT, 10Base5, and fiber optics.

frame: a term to describe a logical unit of data encased in a package. This is most often used with EtherNet to describe the packetized data it uses. An EtherNet frame has a definite beginning and end, and checksums contained within it to not only verify its error free transmission of a packet (and re-transmission if an error is found) so that higher networking layers perceive an error-free layer below them.

header: this is the beginning or "head" of a packet that include information about the packet that is useful for the packet's purpose. In the case of IP, routing information is included, and with TCP, sequence numbers to keep track of the different packets that may arrive out of order, and with many kinds of protocols, checksums to verify that data is error free.

host: a machine, or node that accepts, or offers shares to resources on a network. A single machine not on a network is seldom thought of as a host.

ICMP: Internet Control Messaging Protocol which is used to convey network status messages between hosts. Messages like, "network unreachable" often come from ICMP.

The IEEE is an International group of Electricians and Electrical Engineers that get together to hammer out international industry standards.

IGMP: Internet Group Management Protocol - just knowing that this exists is all that is needed for this paper. It is not discussed in detail.

interface: used to describe a port on where data may flow into our out of a machine. Also used to describe the software and operating system reference to an intangible port where to send or retrieve data.

IP: Internet protocol - This is a Network Layer protocol that is rout-able. An IP header is described in better detail in this paper. IP carries TCP, UDP, and ICMP just to name a few protocols.

LAN (See Local Area Network)

latency: a measure in time of how long it takes for a packet to get from one location to another. A high measure of latency means, a long time is required for a packet of information to arrive to its destination.

Local Area Network: A collection of machines connected to each other so that when turned on, may share resources. This describes both the machines or hosts and the networking equipment, and cables as well as the systems that run on the machines that deal with the network.

mangled: destroyed, or obfuscated

media: something n which data is transmitted, or conveyed. For the purposes of this paper, media can be paper, floppy disks, or even cables. All of these are capable of transmitting data

network: a collection of hosts. See LAN.

Network Layer: this is layer 3 of the ISO, OSI 7 layer model, and the 5 layer TCP/IP reference model. It is used for routing, and with the TCP/IP suite is IP .

NNTP: Net News Transfer Protocol - this is one of the protocols used to move messages posted on USENET to be copied and moved.

packet: a small collection of data that is packaged in such a way that there is a definable beginning and end. A packet may be of arbitrary size.

Physical Layer: This is layer 1 of the ISO, OSI 7 layer model, and the TCP/IP 5 layer model. It includes the physical media: cables, microwaves, networking equipment like hubs, and repeaters.

protocol: an agreed upon system for communicating. English is a language that has rules, and systems for conveying information and data. Though the rules for English are more complex than most networking protocols, English can be thought of as a protocol.

route: a path, or traversed section of media.

router: a device responsible for directing packets to a path that helps them to arrive at the destination specified in their header.

SONET: A kind of high speed networking available from the phone company in some areas capable of speeds over 600 Million bits per second.

TCP: Transmission Control Protocol which operates at the Transport layer. It is responsible for setting up an error free, connection oriented, reliable session.

Transport Layer: layer 4 of the ISO OSI 7 layer model and 5 layer TCP/IP model. Protocols that fit this layer include TCP, UDP, and to some extent ICMP, though many ICMP functions are considered to be part of the Network Layer.

UDP: User Datagram Protocol is an unreliable Network layer protocol bused for cases where loss of data is less important than being able to move the data with the least amount of work in packaging up the data and getting the most data into a packet compared to the size of the header. A UDP header is almost one-third the size of a TCP header.

USENET: used to describe an international BBS where people exchange ideas, thoughts, and advertisements outnumber quality information by 10 to 1. (Increase the order of magnitude by 1 for each year that passes after 1999.)

Attempts have been made to make the tables appear as they should for LYNX users by forcing a common field width for fields being used by padding them with other printable characters. This is meant to allow for LYNX users to see the tables much like the Netscape and other web browser worlds might show them. However, from personal experience, some versions of LYNX still manage to munge the tables, making them use up several pages. It seems to be a problem with how earlier versions of LYNX dealt with tables, but the problem has not been entirely isolated.

Some have asked why this collection of on-line documents is so lacking of graphic content. To them I answer: faster downloads. Many of these pages are smaller than some pictures on many commercial web sites. You do not come here to look at my pictures. You come here to read content. Also, LYNX users benefit from this, and by using ALL text, people with ADA issues are able to use speech recognition software on the text to hear the words.

A Special License: No part of this document may be used for profit without the consent of the author Michael Egan in writing. Content may be duplicated for retransmission for non-profit purposes as long as the copyright and license remain included in their entirety. The content is provided "as-is" and I take no responsibility on the content's truthfulness or consistency. Errors may exist in these documents, but acting upon these errors is left up to the reader to verify by a third party that will take responsibility for fact verification. When notified of errors or inconsistencies, attempts will be made to rectify the errors.

In plan English this is meant to do many things: This copyright is meant to exist so that others may not profit from this work as published in paper form, or by duplicating the content to place advertisements over it and generate income. It is also meant to exist to prevent people from publishing this work as their own and receiving profit from this process on research they did not perform. It is not meant to stop a professor from running off copies to use in their classes for their students. It is also not meant to stop the student from printing up copies for their own education. How depressing it would be to find your work published in book form without your permission, or compensation. Another reason for this Copyright is to limit the effect of the mistakes I have made within this document before I was able to complete it. It would be even sadder to notice my mistakes in print and criticized before I could resolve them. Eventually, after I finish this work, I may retain copyright, but eliminate the license.